Battery-Electric Equipment.
This is mechanically simpler in design than engine-driven equipment. Typically, the high-torque dc electric drive motor is coupled directly to the drive axle through a constant-mesh drive train.

Storage Battery.
These must be replenished frequently either by recharging or by exchanging them for fully charged batteries. Batteries used in a given piece of equipment should provide ample power to operate effectively for an 8-h day as determined by their ampere-hour (Ah) rates.

The Ah rating, to some degree, limits the effective operating range of battery-operated equipment and requires that routine schedules for replenishment are followed. Also, because of the weight of a large storage battery, equipment application is sometimes adversely limited.

Types of Batteries.
The two primary types of batteries used are lead-acid and nickel-ironalkaline. A lead-acid battery will provide 2.0 to 2.3 V per cell, while the nickel-iron-alkaline battery will provide 1.2 V per cell.Voltages used for modern battery-powered mobile equipment are 12, 24, 36, 48, and 72, with some higher voltages used in larger equipment.

Advantages.
The advantages of the lead-acid battery are a lower initial cost, high ampere-hour capacity, and low resistance to self-discharge.The nickel-iron-alkaline battery is desirable because of its longer life expectancy, resistance to physical damage, noncorrosive electrolyte (KOH), and more rapid and less critical recharge rates.

Recharging Times.
These are adjusted for different batteries by dividing the Ah rating of the battery by the 8-h Ah rating of the charger and multiplying by 8. For example, a battery having a 600-Ah rating and a 450-Ah charger will require